Depletion flocculation in colloidal dispersions

Abstract

The destabilisation of colloidal dispersions by free, non-adsorbing polymer molecules in solution is reviewed from both a theoretical and experimental perspective. Consideration is given to the behaviour of polymers in solution in relation to the theories proposed by Flory, de Gennes, and Scheutjens and Fleer. Similarly, the theories describing the behaviour of polymers at or near an interface are also examined together with an outline of their relevance to the depletion interaction. The depletion interaction itself is also comprehensively reviewed, taking into account the different segment density profile theories currently in the scientific literature. Experimental reports of the depletion phenomena are described, covering both hard sphere and soft sphere systems, with both the direct and indirect evidence of the depletion interaction being considered.